Drafting machine



Patented Jan. 2, 1951 DRAFTING MACHINE Morris Sanders and Joseph L.Sanders, Rochelle Park, N. J

Application January 24, 1950, Serial No. 140,212

2 Claims.

This invention relates generally to parallel motion drafting devices ofthe kind in which the several tools which the draftsman handles mostfrequently are embodied, in principle, in one unit to obviate thenecessity of a draftsman reaching about for a required tool and therebyenabling the draftsman to keep his attention concentrated directly uponth drawing.

Drafting devices of this character are common in which adjacent ends oftwo arms are pivoted together, the free end of one arm being secured tothe remote side of a drafting board while the free end of the other armis provided with a head comprising a protractor and straight edges whichare in fixed angular relation and move about the center of theprotractor as an axis.

Hitherto the arrangement of drafting machines of the endless band andpulley type, to which this invention particularly relates, has been suchthat the protractor is situated under the arms containing the endlessband, making it difficult to observe the markings on the protractor whenthe machine is to be set at certain angles; or in machines having theprotractor above the arms, the mechanical arrangement for setting thesemachines automatically to certain prescribed angles must be actuatedfrom a single particular point.

One object of this invention is to provide an arrangement whereby theprotractor is visible in all positions of the arm, and yet having meansfor the automatic setting of the machine to certain prescribed anglesarranged so that it may be actuated without the necessity for theoperator to move his hand or to change the position of his hand.

Another object of this invention is to provide means for disengaging theautomatic indexing mechanism, so as to enable the operator to set thearms in any position and lock the arms in that position.

Another object of this invention is to provide means so that theoperator need not observe the protractor while setting the machine tocertain prescribed angles, but may arrive at a desired angle throughaudible means.

Another object of this invention is to provide means for compensatingfor the deflection of the arms at the elbow by boring the bearin seat inthe arm of the anchor at the necessary angle from the vertical, so thatthe deflection automatically is compensated for equally in all positionsof the arms.

Another important object of this invention is to provide means forparking the machine when not in use, so that the entire surface of thedrawing board is free and clear, and yet retaining the parallelpositions of the arms, even on an inclined board.

With the foregoing and other objects in view which will appear as thedescription proceeds, the invention consists of certain novel details ofconstruction and combinations of parts hereinafter more fully describedand pointed out in the claims, it being understood that changes may bemade in the construction and arrangement of parts without departing fromthe spirit of the invention as claimed.

In the accompanying drawing a preferred form of the invention has beenshown.

In said drawing:

Figure 1 is a top plan view of the entire machine in parking position;

Figure 2 is an enlarged, fractional top view and sectional view on theline 2-2 of Figure 3 of the head assembly;

Figure 3 is a sectional view of the head assembly on the line 3-3 ofFigure 2;

Figure 4 is an enlarged fractional view of the head assembly;

Figur 5 is an enlarged fractional sectional view, as the sectionalportion of Figure 2, but showing some of the parts in positions whichdiffer from their positions shown in Figure 2; and,

Figure 6 is a fractional sectional view on the line 66 of Figure 2.

Similar reference characters refer to'similar parts throughout theseveral views.

Referring first to Figure 1, the drafting machine includes four housingsI held apart by the tubes 2 through which the endless bands 3 pass. suchhousing is mounted pivotally at the anchor which consists of a bracket laffixed to the drawing board 5 by any suitable, well known means.

Referring to Figures 2 to 5, the head consists of a housing I into whicha needle bearing 1 (Figure 3) has been pressed. A tubular shaft 29rotates freely in the bearing 1 and is affixed securely to a casting 30,which preferably is made as a unit with a combination protractor head 31and a pulley portion 32. A belt or an endless band 3 passes round thepulley portion 32. Rotating freely inside the tubular shaft 29 is ashaft 33, the upper portion of which is securely afiixed in the hub of aVernier plate 34. This vernier plate. 34 fits into the annular bore ofthe protractor head 3| and is rotatable therein. To the lower portion ofthe shaft 33 is affixed a rule holder plate 42, which preferably isformed as a unit with a parking tongue section 59.

One.

tion of said rocker arm to which said cross-slide is pivoted and beingadapted for engaging the notches in the periphery of said notched disk,a pawl adapted for engaging the peripheral notches of said ring-shapedplate and being pivotally connected to said cross-slide, as well as tosaid protractor head, a bolt rotatably extended through said protractorhead, a thumb lock lever having a cam portion adapted for engaging saidpawl and being secured to one end of said bolt, a clamp plate secured tothe other end of said bolt having a reduced portion which is interposedbetween said ring-shaped plate and said vernier plate, resilient meansinterposed between said protractor head and said rocker arm beingadapted for forcing the latter against said notched disk, and a pinsecured to said anchor bracket being adapted for extending through theperforation in the parking tongue section of said rule holder plate forthe purpose of retaining the device in its parking position.

2. In a drafting machine head, in combination, a housing having a needlebearing in its center, a tubular member encompassed by said needlebearing and being rotatable thereon, a protractor head having a hubportion which is secured to said tubular member, an upright shaftrotatably extended through said tubular member, a perforated vernierplate secured to the upper end of said shaft and being rotatable in saidprotractor head, a ring-shaped plate having a notched outer peripheryand being secured to the lower side of said vernier plate, aperipherically notched disk through whose center said shaft is extendedbeing interposed between said protractor head and said vernier plate, aknurled ring coaxial with the vernier plate being located upon the outerside of said vernier plate, upright pins secured to said knurled ringand extended loosely through the perforations of said vernier plate intosaid notched disk, a rocker arm having one of its ends pivoted to saidprotractor head, a cross-slide radially movable in said protractor headbeing pivoted to said rocker arm intermediate its ends, a roller securedto that portion of said rocker arm to which said cross-slide is pivoted,a pawl being adapted for engaging the peripheral notches of saidring-shaped plate and being pivotally connected to said cross-slide aswell as to said protractor head, a bolt rotatably extended through saidprotractor head, a thumb lock lever having a cam portion adapted forengaging said pawl and being secured to one end of said bolt, a clampplate secured to the other end of said bolt having a reduced portionwhich is interposed between said ring-shaped plate and said vernierplate, and a spring interposed between said protractor head and saidrocker arm being adapted for forcing the latter against said notcheddisk.

- MORRIS SANDERS.

JOSEPH L. SANDERS.

No references cited.

